<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>closure</title>
</head>
<body>
  <script>
    function makeSalary (base) {
      return function (performance) {
        return base + performance;
      }
    }

    let salaryLevel1 = makeSalary(12000); 
    let salaryLevel2 = makeSalary(15000);

    console.log(salaryLevel1(2000));
    console.log(salaryLevel2(3000));
  </script>
</body>
</html>